PSI - Issue 72

Mohamed Khodjet Kesba et al. / Procedia Structural Integrity 72 (2025) 164–171

165

1. Introduction In recent years composite materials are widely used in the aerospace industry. The advantages of these materials are derived from their high strength, rigidity and lightness. More importantly, they have the potential to reduce the cost of construction, while improving structural reliability and increasing safety. Aircraft structural parts made of composite materials with polymeric matrix, subject to variables conditions and severe environments, require a good knowledge of their behavior under humidity and temperature, B.Boukert et al (2017) ,(2018) ,(2011) has treated different cases of hygothermal loading on a thick plate, a calculation of stress state for different environmental parameters, a calculation of stress state for different environmental parameters, the aim of this study is to develop a simple method to determine the determine the residual stresses, for transient states of states in polymer matrix thin laminates (A.Benkeddad et al 1995 ,H.Hahn et al 1978 ,Z.Sereir et al 2006,2005,2005,G.Springer et al 1988), since the matrix laminates (A.Benkeddad et al 1995 ,H.Hahn et al 1978 ,Z.Sereir et al 2006,2005,2005,G.Springer et al 1988), as the matrix is very sensitive to these parameters, a degradation of the properties is then observed (A.Tounsi et al 2003,2002,2005,G.Staab et al 1999) a consideration of the degradation of the mechanical properties(S.Tsai 1988, Z.Boualem et al 2011, C.Chamis 2000 ) of the mechanical properties of the material during the variation of the temperature and humidity is made.

Fig. 1:

Diffusion

problem in a composite laminate.

2. Concentration consideration Considering a laminated thin plate of thickness h with a polymer matrix. The two faces are exposed to humid environment HR and a temperature T. The concentration has a unidirectional variation in z (Fig.01). The theory of instantaneous thermal equilibrium is considered (Springer 1988 , S.Tsai 1988), the concentration inside the plate is described by the Fick equation with a diffusivity D (H.Hahn et al 1978, Z.Sereir et al 2006,2005, G.Springer et al 1988 ).

2

( , )

( , )

C z t

C z t





.

(1)

D



z

2

t



z



In case of absorption, concentration takes the following form:

   

   

2 2 

 

  

   

cos( )

C j

C

j

z D t

2

 

z

j z   

2

1

( , )

1 2 1 C C C     ( )

sin

exp

(2)

C z t



 

 

2

h

j

h



h

1

j

